Evolution of bioactive 3, 4-dihydropyrimidin-2(1H)-ones by an efficient heterogeneous Ni-phen MCM-41 mixed ligand complex under green path

The synthesis of 3,4-dihydropyrimidin-2-(1H)-ones (DHPMs) was made by utilizing newly synthesized heterogeneous mixed ligand-based Ni-phen MCM-41 catalyst with variety of aryl aldehydes (viz. electron donating, electron withdrawing, fused, disubstituted and unsaturated substituents), ethylacetoacetate, urea and ethanol as a solvent by using two different energy sources: conventional and ultrasonication methods. The effectiveness of the two methods was compared and found that the formation of Biginelli products in ultrasonication method (65–92% yield at 60 °C, 45 min) is better than the conventional method (63–90% yield at 78 °C, 2 h) by yield, temperature and time of the reaction. The formation, heterogeneous nature and morphology of the catalyst have been characterized by Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), inductively coupled plasma-optical emission spectrometry (ICP-OES), thermogravimetric analysis (TGA) and N₂ adsorption–desorption isotherm (BET) techniques. Moreover, the catalyst was recoverable, reusable and very much efficient for three consecutive runs without any significant loss of its catalytic activity. The heterogeneity nature of the recovered catalyst was checked by hot filtration test.